doc/syntax.tex: Clarify the term `root class'.

diff --git a/doc/syntax.tex b/doc/syntax.tex
index 825aaad..30fcdfb 100644 (file)
--- a/doc/syntax.tex
+++ b/doc/syntax.tex
@@ -726,8 +726,9 @@ The @<list>$[\mbox{@<identifier>}]$ names the direct superclasses for the new
 class.  It is an error if any of these @<identifier>s does not name a defined
 class.  The superclass list is required, and must not be empty; listing
 @|SodObject| as your class's superclass is a good choice if nothing else
-seems suitable.  It's not possible to define a \emph{root class} in the Sod
-language: you must use Lisp to do this, and it's quite involved.
+seems suitable.  A class with no direct superclasses is called a \emph{root
+class}.  It is not possible to define a root class in the Sod language: you
+must use Lisp to do this, and it's quite involved.
 
 The @<properties> provide additional information.  The standard class
 properties are as follows.